This week, Debbie Purdy and I will be arguing for the legalisation of physician-assisted dying at the Battle of Ideas in London. A few years ago I might have been on the other side of the argument.

When I was chairman of the Committee on Ethical Issues in Medicine at the Royal College of Physicians, we twice considered Bills put forward by Lord Joffe proposing to legalise the choice of physician-assisted dying for mentally competent people with terminal illness who were suffering unbearably at the end of their lives. On the first occasion, we decided to oppose the Bill and on the second, because we were divided, we opted for neutrality.

The case for such a Bill to me now seems clear. Unbearable suffering, prolonged by medical care, and inflicted on a dying patient who wishes to die, is unequivocally a bad thing. And respect for individual autonomy — the right to have one’s choices supported by others, to determine one’s own best interest, when one is of sound mind — is a sovereign principle. Nobody else’s personal views should override this.

So where did my initial opposition come from? I was in thrall to numerous incorrect assumptions. But the evidence changed my mind.

Several of my assumptions related to palliative care. Wouldn’t assisted dying be unnecessary if the best palliative care were universally available? This is not true and I should have acknowledged this from my experience as a doctor for more than 35 years, when I treated patients whose symptoms were uncontrolled even when they had first-rate palliative care. International experience also confirms that palliative care fails some patients. For the last ten years, assisted suicide has been legal in Oregon under the Death with Dignity Act. Oregon has among the best palliative care of all the states in America and yet nearly 90 per cent of those seeking assisted dying do so from within those services.

I was advised that that the availability of assisted dying as an “easy” option would inhibit investment in palliative care. Again, international experience does not support this. In many countries, legalisation of voluntary euthanasia has been accompanied by increasing investment in palliative care services. In Oregon the proportion of people dying in hospice care has more than doubled since the Death with Dignity Act was introduced.

I also shared the worry that legalising assisted suicide would break down trust between doctor and patient. This is not borne out by the evidence. A survey of nine European countries put levels of trust in the Netherlands at the top. And this is not surprising: in countries with assisted dying, discussion of end-of-life care is open, transparent, honest and mature, not concealed beneath a cloud of ambiguity, as it is in the UK. And the knowledge that your doctor will not abandon the therapeutic alliance with you at your hour of greatest need will foster, not undermine, trust.

I was also concerned that legalising assisted suicide would take us to the top of a slippery slope leading to the involuntary euthanasia of people who do not wish to die. In fact, to use the ethicist John Harris’s phrase, if there is a slippery slope, legislation would apply crampons rather than skis.

In Oregon, where assisted dying legislation is close to the Joffe proposal, the numbers and kinds of people being helped to die have not changed over a decade. The Dutch experience was to me decisive. Rates of non-voluntary euthanasia (ie, doctors actively ending patients’ lives without having been asked by them to do so) decreased from 0.8 per cent of all deaths in 1991 (1,000 deaths) to 0.4 per cent in 2005 (550 deaths).

In the UK, a study published in Palliative Medicine this year found that more than 1 in 200 deaths were assisted, three fifths of which were cases of ending life without explicit request. This means that a few thousand people each year receive assistance to die. The present clinical, ethical and legal fudge — in which ploys such as continuous sedation, and starvation and dehydration, are used to get round the prohibition on assisted dying — is unacceptable.

As a geriatrician, I was also worried that assisted dying would be offered to, or imposed upon, those who are most disempowered. A very detailed analysis of the data in Oregon has shown that there is an under-representation of those groups and an over-representation of comparatively well-off, middle-class white people — feisty characters who are used to getting their own way.

These were the facts that prompted me to change my mind. Even those who accepted these facts still opposed legislation on the grounds that only a small minority of dying people would seek assistance and an even smaller number would use the prescription. Wouldn’t legislation prove a sledgehammer to crack a nut?

Well, I happen to believe that even small numbers of people going through unbearable hell are important. The availability of assisted dying would bring much comfort to many more sufferers than actually use it because it brings a sense of having some control.

Death from dehydration and starvation in patients who have no means of securing an end to their suffering other than by refusing food and fluids, or botched suicides, reflect the unspeakable cruelty of the present law. To accede to someone’s request for assisted dying under the circumstances envisaged in the Joffe Bill is not to devalue human life, or devalue the life of a particular human being, or to collude in their devaluing their own life. It is to accept their valuation of a few remaining days or weeks of life that they do not wish to endure.

As a result of the courageous action of Debbie Purdy, supported by Dignity in Dying, those who assist their loved ones on grim pilgrimages to Switzerland may be confident that they will not face prosecution. But we have a legal vacuum. Legalisation of physician-assisted dying is needed urgently.

Raymond Tallis is a writer and physician. His latest book is The Kingdom of Infinite Space: A Fantastical Journey Around Your Head (Atlantic Books)

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